Carbon-14 Dating - Tracer: A substance, usually a labeled element, used to follow a complex sequence of biochemical reactions, as in an animal body, to locate diseased cells and tissues, to determine physical properties, etc. Half-life: The time required to for half the original nuclides to decay. Metabolic Processes: The chemical and physical processes continuously going on in living organisms and cells. Isotopes: One of two or more atoms of the same element that have the same number of protons in their nucleus but different numbers of neutrons. Carbon-14 Dating Radio-carbon dating is a method of obtaining age estimates on organic materials. The word "estimates" is used because there is a significant amount of uncertainty in these measurements. Each sample type has specific problems associated with its use for dating purposes, including contamination and special environmental effects. More information on the sources of error in carbon dating are presented at the bottom of this page. The method was developed immediately following World War II by Willard F. Libby and coworkers and has provided age determinations in archeology, geology, geophysics, and other branches of science.

Radiocarbon dating estimates can be obtained on wood, charcoal, marine and freshwater shells, bone and antler, and peat and organic-bearing sediments. They can also be obtained from carbonate deposits such as tufa, calcite, marl, dissolved carbon dioxide, and carbonates in ocean, lake and groundwater sources. Carbon dioxide is distributed on a worldwide basis into various atmospheric, biospheric, and hydrospheric reservoirs on a time scale much shorter than its half-life. Measurements have shown that in recent history, radiocarbon levels have remained relatively constant in most of the biosphere due to the metabolic processes in living organisms and the relatively rapid turnover of carbonates in surface ocean waters. However, changes in the atmosphere over the ages are a source of uncertainty in the measurements. Carbon (C) has three naturally occurring isotopes. Both C-12 and C-13 are stable, but C-14 decays by very weak beta decay to nitrogen-14 with a half-life of approximately 5,730 years. Naturally occurring radiocarbon is produced as a secondary effect of cosmic-ray bombardment of the upper atmosphere.

Plants transpire to take in atmospheric carbon, which is the beginning of absorption of carbon into the food chain. Animals eat the plants and this action introduces carbon into their bodies. After the organism dies, carbon-14 continues to decay without being replaced. To measure the amount of radiocarbon left in a artifact, scientists burn a small piece to convert it into carbon dioxide gas. Radiation counters are used to detect the electrons given off by decaying C-14 as it turns into nitrogen. The amount of C-14 is compared to the amount of C-12, the stable form of carbon, to determine how much radiocarbon has decayed, thereby dating the artifact.

Exponential Decay Formula: A = A0* 2^(-t/k) Where "A" is the present amount of the radioactive isotope, "A0" is the original amount of the radioactive isotope that is measured in the same units as "A." The value "t" is the time it takes to reduce the original amount of the isotope to the present amount, and "k" is the half-life of the isotope, measured in the same units as "t." The applet allows you to choose the C-14 to C-12 ratio, then calculates the age of our skull from the formula above. Uncertainty in Carbon Dating As mentioned above, there is significant uncertainty in carbon dating. There are several variables that contribute to this uncertainty. First, as mentioned previously, the proportions of C-14 in the atmosphere in historic times is unknown. The C-14:C-12 atmospheric ratio is known to vary over time and it is not at all certain that the curve is “well behaved.” Complicating things further, various plants have differing abilities to exclude significant proportions of the C-14 in their intake. This varies with environmental conditions as well.

The varying rates at which C-14 is excluded in plants also means that the apparent age of a living animal may be affected by an animal's diet. An animal that ingested plants with relatively low C-14 proportions would be dated older than their true age. Attempts are often made to index C-14 proportions using samples of know age. While this may be useful to eliminate the uncertainty of atmospheric proportions of C-14, it does not compensate for local conditions such as which plant species are in the diet. The uncertainty in the measurement leads some to conclude that the method is far less predictive of age than is commonly supposed, especially for older samples. Last updated on October 28, 2010 Carbon-14 Dating Carbon-14 Dating ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Most everyone has heard of Carbon dating on the news or elsewhere sometime in the past years. Ever wonder what ï¿½Carbon datingï¿½ means and why it is so important?

In this article I hope to explain the theoretical and physical science behind Carbon dating, and discuss how it affects our lives and the validity of the process. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Scientists use Carbon dating for telling the age of an old object, whose origin and age cannot be determined exactly by normal means. Because of this method Chemistry has become intertwined with History, Archeology, Anthropology, and Geology. (Poole) Many items that have been thought to come from one time have been tested and found out to actually come from a few thousands years beforehand. Places where historians believed that human civilization came to exit say, only 2,000 years ago, have actually been proven to have had some form of human civilization more than 4,000 years ago. (Poole) Fine art collectors have used Carbon dating to determine if a piece of antique art is actually genuine. Some have saved themselves several thousands of dollars by testing the piece before they bought it and finding out that it is not the original, but a very clever modern copy. (Poole) But how is this done?

What are the ides behind carbon dating? ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Atoms of given elements have different Isotopes. Isotopes are atoms of the same element, i.e. they have the same number of Protons and Electrons in the atom, but they have a different number of Neutrons in the nucleus, so they have different atomic masses. (Jones & Atkins) The element Carbon is in all living things, it is a basic building block for the construction of organic material. The normal molar mass of Carbon is around 12, however there are a few Carbon atoms that have a molar mass of about 13, and even fewer that have a molar mass of about 14. These atoms have one or two more neutrons in the nucleus than most Carbon atoms. Scientists call the isotope with molar mass around 14, Carbon-14. Carbon-14 is manufactured in the upper atmosphere by the action of cosmic rays.

(Ham, Snelling, & Wieland) Ordinary nitrogen is converted into Carbon-14; however it is not a stable element. It turns out to be radioactive and decays over time. All organic material has decaying Carbon-14 in it. However, plants and animals that are still alive constantly replace the supply of carbon in their systems and so the amount of Carbon-14 in the system stays almost constant. Once a plant or animal dies the Carbon is no longer being regenerated and so the Carbon-14 starts to decay. In this way, by measuring the amount of Carbon-14 in the body of a prehistoric animal or plant, a scientist can deduce when the plant or animal died. All radioactive materials have a half-life. If you have a certain amount of a radioactive material, its half-life is the time it takes for half of the material you started out with to decay. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Carbon-14 decays back into nitrogen.

This is a first order reaction equation and the rate at which it the reaction proceeds over time can be modeled by the equations: Rate=k[C14] [C14 at t=t] = [C14 at t=0](e^-kt) Ln[C14 at t=0] ï¿½ Ln[C14 at t=t] = kt Ln([C14 at t=0] / [C14 at t=t]) = kt To get the half-live of Carbon-14 we let [C14 at t=t] = .5[C14 at t=0] and the equation simplifies to: Ln2 = k(half-life) ,ï¿½ where k is the rate constant fro C14 ï¿½The half-life of a first-order reaction is characteristic of the reaction and independent of the initial concentration. A reaction with a large rate constant has a short half-life.ï¿½ (Jones & Atkins) Willard F. Libby Was the man who first developed the idea and procedure for Carbon dating. He measured the half-life of Carbon-14 to be about 5,568 years.

However after about 50,000 years there is so little Carbon-14 left in the specimen that it is very hard, almost impossible, to calculate its age. (Van Der Merwe) Libby ran many tests on items where the age was known, or estimated by other means. His test results came rather close, to within plus or minus a few hundred years. (Poole) In the laboratory, samples must be processed and cleaned so that there is no material on them that might throw off the age reading. Then the sample is burned and passes through a completely sterile vacuum system as Carbon dioxide gas. The gas is then subjected to more purifying procedures. Afterward the gas is stored in a tube insulated by Mercury and Lead, so as to minimize the chances of the sample being affected by radiations from the atmosphere. When a Carbon-14 atom disintegrates fine instruments detect the action, a light flashes on a control panel, and a counter records the number of decaying atoms. By this method the scientist can keep track of how many atoms are decomposing per minute and per second. (Poole) This sounds great!

We are now ably to date anything we want, even that something at the back of the fridge, and know how old it is within a few hundred years, but are there any problems with the Carbon dating method? Unfortunately there are. In order to know how long a sample of radioactive material had been decomposing we need three variables defined, how much of the sample we have left now, what the half-life of the sample is, and how much of the sample we started out with. For Carbon dating we have already experimentally measured the amount of Carbon-14 left, and Libby has already measured the half-life of Carbon-14 to an acceptable exactness, however how much Carbon-14 was there in the specimen at the time of death. The amount of Carbon-14 in an organic body is constant with the amount of Carbon-14 in the atmosphere. Thus specimens have the same amount of carbon-14 in them as the rest of the atmosphere at the time that the specimen lived. However, if we could measure the amount of Carbon-14 in the atmosphere when they lived, we would be living during the time and there would be no reason for dating.

(Ham, Snelling, & Wieland) We know for a fact that the amount of Carbon in the atmosphere has not stayed the same in the past century. A recent proof of that would be the Industrial revolution. Factories put out massive amounts of Carbon, and during that time the concentration of Carbon-14 in the atmosphere increased significantly. Fortunately, Libby was a smart guy and accounted for this discrepancy. He measured the amount of Carbon in the inner layers of trees that were older than the Industrial revolution. He was able to calculate the amount of Carbon-14 in the atmosphere, before the industrial revolution, and adjust his equation accordingly. (Ham, Snelling, & Wieland) However, Libby then assumed that the amount of Carbon in the atmosphere was relatively constant for a very long time up until the Industrial revolution. Can this be assumed to be correct? In the atmosphere the amount of Carbon-14 decaying over time increases with the greater concentration of Carbon-14 in the atmosphere. Eventually the reaction would reach some equilibrium and the amount of Carbon-14 in the atmosphere would remain constant.

Scientists have calculated that the amount Carbon-14 in the atmosphere would become stable after 30,000 years from the beginning of the reaction. The reaction must have started when the Earth was formed, and thus the reaction would reach equilibrium after the Earth was 30,000 years old. Scientists have assumed that the Earth is many millions of years old, however, no one was living when the earth was formed, and no one has concrete proof as to when the Earth was formed and therefore no one can say exactly how old it is. (Ham, Snelling, & Wieland) Today the rate of production of Carbon-14 is greater than the rate of disintegration. This would seem to indicate a reaction that is not yet in equilibrium. Libbyï¿½s tests showed that the amount of Carbon-14 entering the atmosphere was 12% greater than the amount decaying, before the industrial revolution. These results were within his error margins and thus were ignored.

If we do not ignore them, and I think that 12% is a very large error margin,ï¿½ they would seem to suggest that the reaction was in progress less than 30,000 years and a younger Earth, however, again no one has concrete proof. (Ham, Snelling, & Wieland) There are also some tests that have been done that donï¿½t quite match up. For instance, bones of a sabre-toothed tiger, theorized to be between 100,000 and one million years old, gave a Carbon date of 28,000 years. A freshly killed seal, dated using Carbon-14, showed it had died 1300 years ago. Living mollusk shells were dated at up to 2,300 years old. Some very unusual evidence is that living snails' shells showed that they had died 27,000 years ago. (Ham, Snelling, & Wieland) ï¿½"The troubles of the radiocarbon dating method are undeniably deep and serious ... It should be no surprise, then, that fully half of the dates are rejected.

The wonder is, surely, that the remaining half come to be accepted." (Lee, R. E., Radiocarbon, "Ages in Error", Anthropological Journal of Canada, 1981, vol. 19, No. 3, p. 9)ï¿½ (Ham, Snelling, & Wieland) Carbon dating is used now for almost everything old that people want to date. It is taken as fact and used as evidence to gather information on the world and past civilizations. However, Carbon dating is at best a good theory, and that is all it is, a theory. Too many people forget the definition of a theory. Theory is not fact; it is a hypothesis that is supported by some experimental evidence. There have been many theories in the past that have been disproved. I am not saying that Carbon dating is a bad idea. Willard F. Libby was a very brilliant scientist and had some wonderful ideas. We just need to keep it in perspective and not take a theory for a fact. I wonder if I dated that bowl of something or other in my fridge, what age it would be from. Then again, I am not completely sure itï¿½s dead.

Carbon 14 Dating Calculator Carbon 14 Dating Calculator To find the percent of Carbon 14 remaining after a given number of years, type in the number of years and click on Calculate. Years Carbon 14 left = percent To find the years that have elapsed from how much Carbon 14 remains, type in the C-14 percent and click on Calculate. Percent C-14 Info about c14 Outside the range of recorded history, calibration of the 14 clock is not possible. This means the above calculations are only evolution speculation and NOT backed up by real science. Gen1.org Denying Evolution Evolution=Millions Of Years + Your Imagination How does the carbon ‘clock’ work? Is it reliable? What does carbon dating really show? What about other radiometric dating methods? Is there evidence that the earth is young? The carbon-14 method, when corrected for the effects of the Flood, can give useful results, but needs to be applied carefully. It does not give dates of millions of years and when corrected properly fits well with the biblical Flood.

20 Chapters (More than 60 of the most asked questions about Creation, evolution, and the book of Genesis answered!) Gen1.org Denying Evolution Evolution=Millions Of Years + Your Imagination New Light on Radiometric Dating (CreationMoments.com) Most people find the subject of radiometric dating too technical to understand. Until recent years, scientists who believe in creation haven't had the necessary resources to explore radiometric dating in detail. A 10 gram sample of U-238Now that has changed, and some important discoveries are being made. When granite rock hardens, it freezes radioactive elements in place. The most common radioactive element in granite is Uranium-238. This element is locked in tiny zircons within the granite. As part of the decay process, helium is produced. While it stays within the zircon for a period of time, being a very small atom, helium escapes the zircon within a few thousand years. When creation scientists studied granite samples, they made interesting discoveries. The samples were from a mile below the earth, which, according to inflated evolutionary years, were 1.5 billion years old.

The helium still locked in the samples was studied as well as the rate at which the helium diffused from the rock. They concluded that the helium in the rock was 100,000 times more plentiful than it should have been if the rocks were really 1.5 billion years old. They concluded that their findings are consistent with an Earth that is about 6,000 years old. As our knowledge continues to grow, what we know continues to be in agreement with Scripture. How Accurate Is Radiocarbon Dating? Radiocarbon ages less than 3,500 years old are probably accurate. However, before accepting any radiocarbon date, one should know how the technique works, its limitations, and its assumptions. One limitation is that the radiocarbon technique dates only material that was once part of an animal or plant, such as bones, flesh, or wood. It cannot date rocks directly. To understand the other capabilities and limitations of radiocarbon dating, we must understand how it works and consider the flood. Most carbon atoms weigh 12 atomic mass units. However, roughly one in a trillion carbon atoms weighs 14 atomic units. This carbon is called carbon-14.

It is also called radio carbon because it is radio active (but not dangerous). Half of it will decay in about 5,730 years to form nitrogen. Half of the remainder will decay in another 5,730 years, and so on. Cosmic radiation striking the upper atmosphere converts about 21 pounds of nitrogen each year into radiocarbon (carbon-14). Most carbon-14 quickly combines with oxygen to form radioactive carbon dioxide, which then spreads throughout the atmosphere. Plants take in carbon dioxide, incorporating in their tissues both carbon-14 (unstable) and normal carbon-12 (stable) in the same proportion as they occur in the atmosphere . Carbon-14 then moves up the various food chains to enter animal tissue�again, in about the same ratio carbon-14 has with carbon-12 in the atmosphere. When a living thing dies, its radiocarbon loss (decay) is no longer balanced by intake, so its radiocarbon steadily decreases with a half-life of 5,730 years. If we knew the amount of carbon-14 in an organism when it died, we could attempt to date the time of death.

The key questions then are: �Has the atmospheric ratio of carbon-14 to carbon-12 changed in the past, and if so, why and how much?� The assumption usually made, but rarely acknowledged, is that the ratio of carbon-14 to carbon-12 in the atmosphere before the industrial revolution has always been the same�about one in a trillion. Actually, that ratio may have been quite different. For example, a worldwide flood would uproot and bury preflood forests. Afterward, less carbon would be available to enter the atmosphere from decaying vegetation. With less carbon-12 to dilute the carbon-14 continually forming from nitrogen in the upper atmosphere, the ratio of carbon-14 to carbon-12 in the atmosphere would increase. If the atmosphere's ratio of carbon-14 to carbon-12 has doubled since the flood and we did not know it, radiocarbon ages of things living soon after the flood would appear to be one half-life (or 5,730 years) older than their true ages. If that ratio quadrupled, organic remains would appear 11,460 (2 x 5,730) years older, etc.

Therefore, a �radiocarbon year� would not correspond to an actual year. As explained in recent measurements show that the ratio of carbon-14 to carbon-12 has been building up in the atmosphere. However, for the last 3,500 years, the increase in the ratio has been extremely slight. Radiocarbon dating of vertical sequences of organic-rich layers at 714 locations worldwide has consistently shown a surprising result. Radiocarbon ages do not increase steadily with depth, as one might expect. Instead, they increase at an accelerating rate. In other words, the concentration of carbon-14 is unexpectedly low in the lower organic layers. As one moves to higher and higher layers, this concentration increases, but at a decreasing rate. Tree-ring dating allows us to infer how the atmospheric concentration of carbon-14 changed in the past. Some types of trees growing at high elevations with a steady supply of moisture will reliably add only one ring each year. In other environments, multiple rings can be added in a year. A tree ring's thickness depends on the tree's growing conditions, which vary from year to year. Some rings may show frost or fire damage.

By comparing sequences of ring thicknesses in two different trees, a correspondence can sometimes be shown. Trees of the same species that simultaneously grew within a few hundred miles of each other may have similar patterns. Trees of different species or trees growing in different environments have less similar patterns. Claims are frequently made that wood growing today can be matched up with some scattered pieces of dead wood so that tree-ring counts can be extended back more than 8,600 years. This may not be correct. These claimed �long chronologies� begin with either living trees or dead wood that can be accurately dated by historical methods. This carries the chronology back perhaps 3,500 years. Then the more questionable links are established based on the judgment of a tree-ring specialist. Sometimes �missing� rings are added. Each tree ring's width varies greatly around the tree's circumference. Also, parts of a ring may be dead wood. Standard statistical techniques could establish how well the dozen supposedly overlapping tree-ring sequences fit. However, tree-ring specialists have refused to subject their judgments to these statistical tests and would not release their data, so others can do these statistical tests.

Even less reliable techniques claim to be able to calibrate carbon-14 dating back 26,000 years or more. Several laboratories in the world are now equipped to perform a much improved radiocarbon dating procedure. Using atomic accelerators, a specimen's carbon-14 atoms can now be actually counted, giving a more precise radiocarbon date with even smaller samples. The standard, but less accurate, radiocarbon dating technique only counts the rare disintegrations of carbon-14 atoms, which are sometimes confused with other types of disintegrations. This new atomic accelerator technique has consistently detected at least small amounts of carbon-14 in every organic specimen�even materials that evolutionists claim are millions of years old, such as coal. This small, consistent amount is found so often among various specimens that contamination can probably be ruled out. Ancient human skeletons, when dated by this new �accelerator mass spectrometer� technique, give surprisingly recent dates. In one study of eleven sets of ancient human bones, all were dated at about 5,000 radiocarbon years or less! Radiocarbon dating of supposedly very ancient bones should provide valuable information. Why is such testing rare?

Researchers naturally do not waste money on a technique that destroys their specimen and provides no specific age. Therefore, most researchers do not radiocarbon date any organic specimen they think is older than 100,000 years, even if it still contains carbon. All carbon-14 that was once in anything older than 100,000 radiocarbon years would have decayed; its age could not be determined. However, if a bone an evolutionist thinks is a million years old contains any detectable carbon-14, the bone is probably less than 100,000 radiocarbon years. Bones or other organic remains that contain enough carbon and are believed by evolutionists to be older than 100,000 years will be shown to be relatively young in blind radiocarbon tests. This prediction, first published in the 6th Edition (1995), p. 157, has now been confirmed. Very precise measurements now show that most fossils�regardless of presumed �geologic age��have roughly the same ratio of carbon-14 to carbon-12.

(This includes fossil fuels: coal, oil, and methane.) Therefore, this former life must have been living at about the same time�less than 100,000 years ago. Because almost all fossils are preserved in water deposited sediments, all this former life was probably buried in a fairly recent, gigantic flood. Radiocarbon dating is becoming increasingly important in interpreting the past. However, one must understand how it works and especially how a flood affected radiocarbon dating. Radiocarbon ages less than 3,500 years are probably accurate. Ages around 40,000 radiocarbon years, which are typical of coal, have much younger true dates�near the time of the flood, roughly 5,000 years ago. Carbon-14 Dating Carbon-14 Dating After reading this section you will be able to do the following: Describe why carbon can be found in all living organisms. Explain how carbon can help determine the age of some objects. As you learned in the previous page, carbon dating uses the half-life of Carbon-14 to find the approximate age of certain objects that are 40,000 years old or younger.

In the following section we are going to go more in-depth about carbon dating in order to help you get a better understanding of how it works. What exactly is radiocarbon dating? Radiocarbon dating is a method of estimating the age of organic material. It was developed right after World War II by Willard F. Libby and coworkers, and it has provided a way to determine the ages of different materials in archeology, geology, geophysics, and other branches of science. Some examples of the types of material that radiocarbon can determine the ages of are wood, charcoal, marine and freshwater shell, bone and antler, and peat and organic-bearing sediments. Age determinations can also be obtained from carbonate deposits such as calcite, dissolved carbon dioxide, and carbonates in ocean, lake, and groundwater sources. How is carbon-14 produced? Cosmic rays enter the earth's atmosphere in large numbers every day and when one collides with an atom in the atmosphere, it can create a secondary cosmic ray in the form of an energetic neutron.

When these energetic neutrons collide with a nitrogen-14 (seven protons, seven neutrons) atom it turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons). Since Nitrogen gas makes up about 78 percent of the Earth's air, by volume, a considerable amount of Carbon-14 is produced. The carbon-14 atoms combine with oxygen to form carbon dioxide, which plants absorb naturally and incorporate into plant fibers by photosynthesis. Animals and people take in carbon-14 by eating the plants. The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant. Maybe one in a trillion carbon atoms are carbon-14. Both Carbon-12 and Carbon-13 are stable, but Carbon-14 decays by very weak beta decay to nitrogen-14 with a half-life of approximately 5,730 years. After the organism dies it stops taking in new carbon. How do scientist use Carbon-14 to determine the age of an artifact?

To measure the amount of radiocarbon left in a artifact, scientists burn a small piece to convert it into carbon dioxide gas. Radiation counters are used to detect the electrons given off by decaying Carbon-14 as it turns into nitrogen. In order to date the artifact, the amount of Carbon-14 is compared to the amount of Carbon-12 (the stable form of carbon) to determine how much radiocarbon has decayed. The ratio of carbon-12 to carbon-14 is the same in all living things. However, at the moment of death, the amount of carbon-14 begins to decrease because it is unstable, while the amount of carbon-12 remains constant in the sample. Half of the carbon-14 degrades every 5,730 years as indicated by its half-life. By measuring the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of the artifact. Review: Carbon-14 dating can determine the age of an artifact that is up to 40,000 years old. Living organisms absorb carbon my eating and breathing.

After burning a small piece of an artifact, scientists compare the amount of Carbon-14 to the amount of Carbon-12 to determine the age of the object. How Carbon-14 is Made - How Carbon-14 Dating Works | HowStuffWorks How Carbon-14 is Made Prev Next Co­smic rays enter the earth's atmosphere in large numbers every day. For example, every person is hit by about half a million cosmic rays every hour. It is not uncommon for a cosmic ray to collide with an atom in the atmosphere, creating a secondary cosmic ray in the form of an energetic neutron, and for these energetic neutrons to collide with nitrogen atoms. When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons). Carbon-14 is radioactive, with a half-life of about 5,700 years. For more information on cosmic rays and half-life, as well as the process of radioactive decay, see How Nuclear Radiation Works .

Up Next Amazing Cave Pictures Carbon-14 in Living Things ­The carbon-14 atoms that cosmic rays create combine with oxygen to form carbon dioxide, which plants absorb naturally and incorporate into plant fibers by photosynthesis. Animals and people eat plants and take in carbon-14 as well. The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant. Maybe one in a trillion carbon atoms are carbon-14. The carbon-14 atoms are always decaying, but they are being replaced by new carbon-14 atoms at a constant rate. At this moment, your body has a certain percentage of carbon-14 atoms in it, and all living plants and animals have the same percentage. NOVA | Radioactive Decay of Carbon-14 Radioactive Decay of Carbon-14 Posted 08.09.12 NOVA In this video excerpt from NOVA's "Hunting the Elements," New York Times technology columnist David Pogue explores how isotopes of carbon can be used to determine the age of once-living matter.

Learn how variations in atomic structure form isotopes of an element and how the three natural isotopes of carbon differ from each other. Meet paleoclimatologist Scott Stine, who uses radiocarbon dating to study changes in climate. Find out what it means for an isotope to be radioactive and how the half-life of carbon-14 allows scientists to date organic materials. Permitted use: Log in to Teachers' Domain to download, share, rate, save, and match to state standards. Source: NOVA: "Hunting the Elements" This media asset was excerpted from NOVA: "Hunting the Elements." Teaching Tips Here are some of the main ideas students should take away from this video: All living things contain carbon. Isotopes are variations of an element; the number of protons in each isotope is the same, but the number of neutrons differs. Carbon has three natural isotopes: carbon-12, carbon-13, and carbon-14. Carbon-14 is a rare version of carbon with eight neutrons. It is radioactive and decays over time. When carbon-14 decays, a neutron turns into a proton and it loses an electron to become nitrogen-14.

The length of time it will take for half the amount of carbon-14 to decay is known as its half-life. Here's additional information not featured in this video that can be shared with students: Carbon dating measures the ratio of carbon-14 to carbon-12 and uses the known half-life of carbon-14 to estimate the age of organic material. Questions for Discussion What is the most common form of carbon? How is carbon-14 different? What does it mean to say that an isotope is unstable? Describe the radioactive decay of carbon-14. How does the scientist in the video use carbon to help study changes in climate? Transcript DAVID POGUE (Technology Guru): Scientists now know that most elements come in more than one version. The different versions are called isotopes. Consider carbon, the backbone of life. It has three natural isotopes, or versions. Each has six protons and six electrons. That's what makes them all carbon. The difference between them is the number of neutrons in the nucleus. Neutrons are electrically neutral particles that act as glue to hold atoms together. What we think of as normal carbon is called carbon-12: six protons plus six neutrons.

But about one percent of carbon atoms have an extra neutron, giving them seven. They're called carbon-13. And about one in a million have eight neutrons. That's carbon-14. And that rare version of carbon has proven to be a crucial tool for unlocking the past. Several times a year, scientist Scott Stine travels to the shores of Mono Lake, near Yosemite National Park. So this, then, is Mono Lake. SCOTT STINE (Paleoclimatologist): Mono Lake, yeah. Right here, at the foot of the Sierra Nevada. DAVID POGUE: He's studying the long history of droughts in California, trying to determine how frequently they occur and how long they last. Over the millennia, the water level has risen and fallen, as the area has cycled between wet periods and dry times. So that sandy area should be the level? SCOTT STINE: During times when the climate was dry, Mono Lake dropped down, exposed the shore lands, and allowed trees and shrubs to grow. When the dry periods ended and the water level rose, the trees drowned, marking the end of the droughts. Since then, the remains of those trees have been well preserved by the arid climate.

These droughts were long and persistent. DAVID POGUE: To determine how long ago these droughts occurred, Scott is using carbon-14 to date the trees. Unlike the other natural isotopes of carbon, carbon-14 is unstable. Over time, its atoms begin to deteriorate. One of its neutrons turns into a proton and spits out an electron. Now, with seven protons instead of six, it's turned into nitrogen. That process is called radioactive decay. And scientists know exactly how long it will take for half of any amount of carbon-14 to decay away. Scientists call that time its "half-life." Living things constantly replenish the carbon in their bodies, animals from food, plants from the atmosphere, but after death, that process stops. The amount of carbon-12 stays the same, but the carbon-14 decays away, at a constant rate, making carbon-14 a ticking atomic clock. Carbon, Chemical Element - structure, reaction, water, uses, elements, proteins, metal, gas PRONUNCIATION CAR-bun Carbon is such an important element that an entirely separate field of chemistry is devoted to this element and its compounds.

Organic chemistry is the study of carbon compounds. Discovery and naming Humans have been aware of carbon since the earliest of times. When cave people made a fire, they saw smoke form. The black color of smoke is caused by unburned specks of carbon. The smoke may have collected on the ceiling of their caves as soot. Later, when lamps were invented, people used oil as a fuel. When oil burns, carbon is released in the reaction, forming a sooty covering on the inside of the lamp. That form of carbon became known as lampblack. Lampblack was also often mixed with olive oil or balsam gum to make ink. And ancient Egyptians sometimes used lampblack as eyeliner. One of the most common forms of carbon is charcoal. Charcoal is made by heating wood in the absence of air so it does not catch fire. Instead, it gives off water vapor, leaving pure carbon. This method for producing charcoal was known as early as the Roman civilization (509 B.C.-A.D. 476). French physicist René Antoine Ferchault Reaumur (1683-1757) believed carbon might be an element.

He studied the differences between wrought iron, cast iron, and steel. The main difference among these materials, he said, was the presence of a "black combustible material" that he knew was present in charcoal. Carbon was officially classified as an element near the end of the eighteenth century. In 1787, four French chemists wrote a book outlining a method for naming chemical substances. The name they used, carbone, is based on the earlier Latin term for charcoal, charbon. Coal, soot (nearly pure carbon), and diamonds are all nearly pure forms of carbon. Physical properties Carbon exists in a number of allotropic forms. Allotropes are forms of an element with different physical and chemical properties. Two allotropes of carbon have crystalline structures: diamond and graphite. In a crystalline material, atoms are arranged in a neat orderly pattern. Graphite is found in pencil "lead" and ball-bearing lubricants. Among the non-crystalline allotropes of carbon are coal, lampblack, charcoal, carbon black, and coke. Carbon black is similar to soot. Coke is nearly pure carbon formed when coal is heated in the absence of air.

Carbon allotropes that lack crystalline structure are amorphous, or without crystalline shape. The allotropes of carbon have very different chemical and physical properties. For example, diamond is the hardest natural substance known. It has a rating of 10 on the Mohs scale. The Mohs scale is a way of expressing the hardness of a material. It runs from 0 (for talc) to 10 (for diamond). The melting point of diamond is about 3,700°C (6,700°F) and its boiling point is about 4,200°C (7,600°F). Its density is 3.50 grams per cubic centimeter. On the other hand, graphite is a very soft material. It is often used as the "lead" in lead pencils. It has a hardness of 2.0 to 2.5 on the Mohs scale. Graphite does not melt when heated, but sublimes at about 3,650°C (6.600°F). Sublimination is the process by which a solid changes directly to a gas when heated, without first changing to a liquid.

Its density is about 1.5 to 1.8 grams per cubic centimeter. The numerical value for these properties varies depending on where the graphite originates. The amorphous forms of carbon, like other non-crystalline materials, do not have clear-cut melting and boiling points. Their densities vary depending on where they originate. Chemical properties Carbon does not dissolve in or react with water, acids, or most other materials. It does, however, react with oxygen. It burns in air to produce carbon dioxide (CO 2 ) and carbon monoxide (CO). The combustion (burning) of coal gave rise to the Industrial Revolution (1700-1900). Another highly important and very unusual property of carbon is its ability to form long chains. It is not unusual for two atoms of an element to combine with each other. Oxygen (O 2 ), nitrogen (N 2 ), hydrogen (H 2 ), chlorine (Cl 2 ), and bromine (Br 2 ) are a few of the elements that can do this. Some elements can make even longer strings of atoms. Rings of six and eight sulfur atoms (S 6 and S 8 ), for example, are not unusual.

Carbon has the ability to make virtually endless strings of atoms. If one could look at a molecule of almost any plastic, for example, a long chain of carbon atoms attached to each other (and to other atoms as well) would be evident. Carbon chains can be even more complicated. Some chains have side chains hanging off them. Arrangement of carbon atoms in a diamond. There is almost no limit to the size and shape of molecules that can be made with carbon atoms. (See accompanying diagrams.) Buckyballs are a recently discovered form of pure carbon. These spheres are made up of exactly 60 linked carbon atoms. Occurrence in nature Carbon is the sixth most common element in the universe and the fourth most common element in the solar system. It is the second most common element in the human body after oxygen. About 18 percent of a person's body weight is due to carbon. The black color of smoke is caused by unburned specks of carbon. Carbon is the 17th most common element in the Earth's crust. Its abundance has been estimated to be between 180 and 270 parts per million. It rarely occurs as a diamond or graphite. Carbon reacts with oxygen by burning in air.

Both allotropes are formed in the earth over millions of years, when dead plant materials are squeezed together at very high temperatures. Diamonds are usually found hundreds or thousands of feet beneath the earth's surface. Africa has many diamond mines. Carbon also occurs in a number of minerals. Among the most common of these minerals are the carbonates of calcium (CaCO 3 ) and magnesium (MgCO 3 ). Carbon also occurs in the form of carbon dioxide (CO 2 ) in the atmosphere. Carbon dioxide makes up only a small part of the atmosphere (about 300 parts per million), but it is a crucial gas. Plants use carbon dioxide in the atmosphere in the process of photosynthesis. Photosynthesis is the process by which plants convert carbon dioxide and water to carbohydrates (starches and sugars). This process is the source of life on Earth. Carbon also occurs in coal, oil, and natural gas. These materials are often known as fossil fuels. They get that name because of the way they were formed. They are the remains of plants and animals that lived millions of years ago. When they died, they fell into water or were trapped in mud. Over millions of years, they slowly decayed.

The products of that decay process were coal, oil, and natural gas. Some forms of coal are nearly pure carbon. Oil and natural gas are made primarily of hydrocarbons, which are compounds made of carbon and hydrogen. Isotopes Three isotopes of carbon occur in nature, carbon-12, carbon-13, and carbon-14. One of these isotopes, carbon-14, is radioactive. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope. Five artificial radioactive isotopes of carbon are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Artificial radioactive isotopes can be made by firing very small particles (such as protons) at atoms. These particles stick in the atoms and make them radioactive. Carbon-14 has some limited applications in industry.

For example, it can be used to measure the thickness of objects, such as sheets of steel. The steel must always be the same thickness. Carbon is the sixth most common element in the universe and the fourth most common element in the solar system. In this process, a small sample of carbon-14 is placed above the conveyor belt carrying the steel sheet. A detection device is placed below the sheet. The detection device counts the amount of radiation passing through the sheet. If the sheet gets thicker, Less radiation gets through. If the sheet gets thinner, more radiation gets through. The detector records how much radiation passes through the sheet. If the amount becomes too high or too low, the conveyor belt is turned off. The machine making the sheet is adjusted to produce steel of the correct thickness. The most important use of carbon-14 is in finding the age of old objects (see accompanying sidebar for more information). Extraction Diamond, graphite, and other forms of carbon are taken directly from mines in the earth. Diamond and graphite can also be made in laboratories.

Synthetic diamonds, for example, are made by placing pure carbon under very high pressures (about 800,000 pounds per square inch) and temperatures (about 2,700°C). The carbon is heated and squeezed in the same way organic material is heated and squeezed in the earth. Today, about a third of all diamonds used are synthetically produced. Carbon-14 dating W hen an organism is alive, it takes in carbon dioxide from the air around it. Most of that carbon dioxide is made of carbon-12, but a tiny portion consists of carbon-14. So the living organism always contains a very small amount of radioactive carbon, carbon-14. A detector next to the living organism would record radiation given off by the carbon-14 in the organism. When the organism dies, it no longer takes in carbon dioxide. No new carbon-14 is added, and the old carbon-14 slowly decays into nitrogen. The amount of carbon-14 slowly decreases as time goes on. Over time, less and less radiation from carbon-14 is produced.

The amount of carbon-14 radiation detected for an organism is a measure, therefore, of how long the organism has been dead. This method of determining the age of an organism is called carbon-14 dating. The decay of carbon-14 allows archaeologists (people who study old civilizations) to find the age of once-living materials. Measuring the amount of radiation remaining indicates the approximate age. Uses There are many uses for carbon's two key allotropes, diamond and graphite. Diamonds are one of the most beautiful and expensive gemstones in the world. But they also have many industrial uses. Because they are so hard they are used to polish, grind, and cut glass, metals, and other materials. The bit on an oil-drilling machine may be made of diamonds. The tool used to make thin tungsten wires is also made of diamonds. Synthetic diamonds are more commonly used in industry than in jewelry. Industrial diamonds do not have to be free of flaws, as do jewelry diamonds. Graphite works well as pencil lead because it rubs off easily. It is also used as a lubricant. Graphite is added to the space between machine parts that rub against each other.

The graphite allows the parts to slide over each other smoothly. Graphite is also used as a refractory. Refractory material can withstand very high temperatures by reflecting heat away from itself. Refractory materials are used to line ovens used to maintain high temperatures. Graphite is used in nuclear power plants. A nuclear power plant converts nuclear energy to electrical power. Graphite acts as a moderator by slowing down the neutrons used in the nuclear reaction. Graphite is used to make black paint, in explosives and matches, and in certain kinds of cathode ray tubes, like the ones used in television sets. Amorphous forms of carbon have many uses. These include the black color in inks, pigments (paints), rubber tires, stove polish, typewriter ribbons, and phonograph records. One form of carbon is known as activated charcoal. The term activated means that the charcoal has been ground into a very fine powder. In this form, charcoal can remove impurities from liquids that pass through. For example, activated charcoal removes color and odor from oils and water solutions. The decay of carbon-14 allows archaeologists (people who study old civilizations) to find the age of once-living materials.

Compounds Carbon dioxide (CO 2 ) is used to make carbonated beverages (it's the fizz in soda pop and beer), in fire extinguishers, and as a propellant in aerosol products. A propellant is a gas that pushes liquids out of a spray can, such as those used for deodorant or hair spray. Carbon dioxide can also be frozen to a solid called dry ice. It is widely used as a way of keeping objects cold. Solid carbon dioxide is most commonly known as dry ice. Carbon monoxide (CO) is another compound formed between carbon and oxygen. Carbon monoxide is a very toxic gas produced when something burns in a limited amount of air. Carbon monoxide is always formed when gasoline burns in the engine of an automobile and is a common part of air pollution. Old heating units can produce carbon monoxide. This colorless and odorless gas can cause headaches, illness, coma, or even death. Carbon monoxide has a few important industrial uses. It is often used to obtain a pure metal from the ore of that metal: It would take a very large book to describe all the uses of organic compounds, which are divided into a number of families.

An organic family is a group of organic compounds with similar structures and properties. The largest organic family is the hydrocarbons, compounds that contain only carbon and hydrogen. Methane, or natural gas (CH 4 ), ethane (C 2 H 6 ), propane (C 3 H 8 ), ethylene (C 2 H 4 ), and benzene (C 6 H 6 ) are all hydrocarbons. Hydrocarbons are used as fuels. Gas stoves burn natural gas, which is mostly methane. Propane gas is a popular camping fuel, used in small stoves and lanterns. Another important use of hydrocarbons is in the production of more complicated organic compounds. Buckyballs and nanotubes In the 1980s, chemists discovered a new allotrope of carbon. The carbon atoms in this allotrope are arranged in a sphere-like form of 60 atoms. The form resembles a building invented by American architect Buckminster Fuller (1895-1983). The building is known as a geodesic dome. Each of the points on the dome is occupied by one carbon atom.

The discoverers named the new form of carbon buckminsterfullerene in honor of Fuller. That name is too long to use in everyday conversation so it is usually shortened to fullerene or buckyball. The discovery of the fullerene molecule was very exciting to chemists. They had never seen a molecule like it. They have been studying ways of working with this molecule. One interesting technique has been to cut open just one small part of the molecule. Then they cut open a small part on a second molecule. Finally, they join the two buckyballs together. They get a double-buckyball. Repeating this process over and over could result in triple-buckyballs, quadruple-buckyballs, and so on. As this process is repeated, the buckyball becomes a long narrow tube called a nanotube. Nanotubes are long, thin, and extremely tiny tubes somewhat like a drinking straw or a long piece of spaghetti. Scientists are beginning to find ways of using nanotubes. One idea is to run a thin chain of metal atoms through the center of a nanotube. This allows it to act like a tiny electrical wire. Nanotubes may completely change many devices that will be made in the future.

Other organic families contain carbon, hydrogen, and oxygen. Methyl alcohol (wood alcohol) and ethyl alcohol (grain alcohol) are the most common members of the alcohol family. Methyl alcohol is used to make other organic compounds and as a solvent (a substance that dissolves other substances). Ethyl alcohol is used for many of the same purposes. It is also the alcohol found in beer, wine, and hard liquor, such as whiskey and vodka. All alcohols are poisonous but some alcohols are more poisonous than others. If not drunk in moderation, alcoholic beverages can damage the body and brain. And, if drunk in large quantities, they can cause death. Methyl alcohol is more toxic than ethyl alcohol. People who have drunk methyl alcohol by mistake have died. The list of everyday products made from organic compounds is very long. It includes drugs, artificial fibers, dyes, artificial colors and flavors, food additives, cosmetics, plastics of all kinds, detergents, synthetic rubber, adhesives, antifreeze, pesticides and herbicides, synthetic fuels, and refrigerants. Health effects Carbon is essential to life. Nearly every molecule in a living organism contains carbon.

The study of carbon compounds that occur in living organisms is called biochemistry (bio- = life + -chemistry ). Carbon can also have harmful effects on organisms. For example, coal miners sometimes develop a disease known as black lung. The name comes from the appearance of the miner's lungs. Instead of being pink and healthy, the miner's lungs are black. The black color is caused by coal dust inhaled by the miner. The longer a miner works digging coal, the more the coal dust is inhaled. That worker's lungs become more and more black. Color is not the problem with black lung disease however. The coal dust in the lungs blocks the tiny holes through which oxygen gets into the lungs. As more coal dust accumulates, more holes are plugged up, making it harder for the miner to breathe. Many miners eventually die from black lung disease because they lose the ability to breathe. Carbon is essential to life. Nearly every molecule in a living organism contains carbon. Carbon monoxide poisoning is another serious health problem. Carbon monoxide is formed whenever coal, oil, or natural gas bums. For example, the burning of gasoline in cars and trucks produces carbon monoxide. Today, almost every person in the United States inhales some carbon monoxide every day.

Small amounts of carbon monoxide are not very dangerous. But larger amounts cause a variety of health problems. At low levels, carbon monoxide causes headaches, dizziness, nausea, and loss of balance. At higher levels, a person can lose consciousness. At even higher levels, carbon monoxide can cause death. Also read article about Carbon from Wikipedia User Contributions:

Question: To which other element does Carbon 14 convert with time?
Answer: Nitrogen